Phylogenetic analysis of the genus Pseudoroegneria and the Triticeae tribe using the rbcl gene

Abstract

Pseudoroegneria are diploid perennial grasses of the Triticeae tribe. The haplome “St” of Pseudoroegneria is shared with several important polyploid species such as Elymus, Kengyilia and, Elytrigia. Due to frequent hybridizations and complex genetic mechanisms, the relationships within Pseudoroegneria, and within the Triticeae, have been heavily disputed. Using the chloroplast rbcL gene I estimated the nucleotide diversity of 8 Pseudoroegneria species, and additionally examined the phylogenetic relationships within Pseudoroegneria and of Pseudoroegneria within the larger context of Triticeae. The estimates of nucleotide diversity indicated that P. tauri and P. spicata species had the highest diversity, while P. gracillima had the lowest. The phylogenetic analysis of Pseudoroegneria placed all P. spicata sequences into a clade separate from the other Pseudoroegneria, while the relationship of the other Pseudoroegneria species could not be determined. Due to the groupings of Pseudoroegneria with the polyploid Elymus, our results strongly support Pseudoroegneria as the maternal genome donor to Elymus. There was also weak support for the idea that P. spicata may be the maternal genome donor to the StH Elymus species.